3 (three) is a
number
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers c ...
,
numeral and
digit. It is the
natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...
following
2 and preceding
4, and is the smallest odd
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...
and the only prime preceding a
square number
In mathematics, a square number or perfect square is an integer that is the square (algebra), square of an integer; in other words, it is the multiplication, product of some integer with itself. For example, 9 is a square number, since it equals ...
. It has religious or cultural significance in many societies.
Evolution of the Arabic digit
The use of three lines to denote the number 3 occurred in many writing systems, including some (like Roman and
Chinese numerals
Chinese numerals are words and characters used to denote numbers in Chinese.
Today, speakers of Chinese use three written numeral systems: the system of Arabic numerals used worldwide, and two indigenous systems. The more familiar indigenous sy ...
) that are still in use. That was also the original representation of 3 in the
Brahmic
The Brahmic scripts, also known as Indic scripts, are a family of abugida writing systems. They are used throughout the Indian subcontinent, Southeast Asia and parts of East Asia. They are descended from the Brahmi script of ancient India ...
(Indian) numerical notation, its earliest forms aligned vertically.
However, during the
Gupta Empire
The Gupta Empire was an ancient Indian empire which existed from the early 4th century CE to late 6th century CE. At its zenith, from approximately 319 to 467 CE, it covered much of the Indian subcontinent. This period is considered as the Gol ...
the sign was modified by the addition of a curve on each line. The
Nāgarī script
The Nāgarī script or Northern Nagari of Kashi is the ancestor of Devanagari, Nandinagari and other variants, and was first used to write Prakrit and Sanskrit. The term is sometimes used as a synonym for Devanagari script.Kathleen Kuiper (2010) ...
rotated the lines clockwise, so they appeared horizontally, and ended each line with a short downward stroke on the right. In cursive script, the three strokes were eventually connected to form a glyph resembling a with an additional stroke at the bottom: ३.
The Indian digits spread to the
Caliphate
A caliphate or khilāfah ( ar, خِلَافَة, ) is an institution or public office under the leadership of an Islamic steward with the title of caliph (; ar, خَلِيفَة , ), a person considered a political-religious successor to th ...
in the 9th century. The bottom stroke was dropped around the 10th century in the western parts of the Caliphate, such as the
Maghreb
The Maghreb (; ar, الْمَغْرِب, al-Maghrib, lit=the west), also known as the Arab Maghreb ( ar, المغرب العربي) and Northwest Africa, is the western part of North Africa and the Arab world. The region includes Algeria, ...
and
Al-Andalus
Al-Andalus DIN 31635, translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label=Berber languages, Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, ...
, when a distinct variant ("Western Arabic") of the digit symbols developed, including modern Western 3. In contrast, the Eastern Arabs retained and enlarged that stroke, rotating the digit once more to yield the modern ("Eastern")
Arabic
Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...
digit "٣".
In most modern Western
typeface
A typeface (or font family) is the design of lettering that can include variations in size, weight (e.g. bold), slope (e.g. italic), width (e.g. condensed), and so on. Each of these variations of the typeface is a font.
There are list of type ...
s, the digit 3, like the other
decimal digit
A numerical digit (often shortened to just digit) is a single symbol used alone (such as "2") or in combinations (such as "25"), to represent numbers in a positional numeral system. The name "digit" comes from the fact that the ten digits (Latin ...
s, has the height of a
capital letter
Letter case is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowercase (or more formally ''minuscule'') in the written representation of certain languages. The writing ...
, and sits on the
baseline. In typefaces with
text figures
Text figures (also known as non-lining, lowercase, old style, ranging, hanging, medieval, billing, or antique figures or numerals) are numerals designed with varying heights in a fashion that resembles a typical line of running text, hence the ...
, on the other hand, the glyph usually has the height of a
lowercase letter
Letter case is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowercase (or more formally ''minuscule'') in the written representation of certain languages. The writing ...
"x" and a
descender
In typography and handwriting, a descender is the portion of a letter that extends below the baseline of a font.
For example, in the letter ''y'', the descender is the "tail", or that portion of the diagonal line which lies below the ''v'' c ...
: "
![Text figures 036](https://upload.wikimedia.org/wikipedia/commons/c/c4/Text_figures_036.svg)
". In some
French text-figure typefaces, though, it has an
ascender instead of a descender.
A common graphic variant of the digit three has a flat top, similar to the letter
Ʒ (ezh). This form is sometimes used to prevent falsifying a 3 as an 8. It is found on
UPC-A
The Universal Product Code (UPC or UPC code) is a barcode#Symbologies, barcode symbology that is widely used worldwide for tracking trade items in stores.
UPC (technically refers to UPC-A) consists of 12 digits that are uniquely assigned to each ...
barcodes and
standard 52-card deck
The standard 52-card deck of French-suited playing cards is the most common pack of playing cards used today. In English-speaking countries it is the only traditional pack used for playing cards; in many countries of the world, however, it is used ...
s.
Mathematics
3 is the second smallest
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...
and the first
odd
Odd means unpaired, occasional, strange or unusual, or a person who is viewed as eccentric.
Odd may also refer to:
Acronym
* ODD (Text Encoding Initiative) ("One Document Does it all"), an abstracted literate-programming format for describing X ...
prime number. It is the first
unique prime
The reciprocals of prime numbers have been of interest to mathematicians for various reasons. They do not have a finite sum, as Leonhard Euler proved in 1737.
Like all rational numbers, the reciprocals of primes have repeating decimal represen ...
, such that the
period length
A periodic function is a Function (mathematics), function that repeats its values at regular intervals. For example, the trigonometric functions, which repeat at intervals of 2\pi radians, are periodic functions. Periodic functions are used th ...
value of
1 of the
decimal expansion
A decimal representation of a non-negative real number is its expression as a sequence of symbols consisting of decimal digits traditionally written with a single separator:
r = b_k b_\ldots b_0.a_1a_2\ldots
Here is the decimal separator, is ...
of its
reciprocal
Reciprocal may refer to:
In mathematics
* Multiplicative inverse, in mathematics, the number 1/''x'', which multiplied by ''x'' gives the product 1, also known as a ''reciprocal''
* Reciprocal polynomial, a polynomial obtained from another pol ...
, 0.333..., is unique. 3 is a
twin prime
A twin prime is a prime number that is either 2 less or 2 more than another prime number—for example, either member of the twin prime pair (41, 43). In other words, a twin prime is a prime that has a prime gap of two. Sometimes the term ''twin pr ...
with
5, and a
cousin prime
In number theory, cousin primes are prime numbers that differ by four. Compare this with twin primes, pairs of prime numbers that differ by two, and sexy primes, pairs of prime numbers that differ by six.
The cousin primes (sequences and in OE ...
with
7, and the only known number
such that
! - 1 and
! + 1 are prime, as well as the only prime number
such that
- 1 yields another prime number,
2. A
triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...
is made of three
sides. It is the smallest non-self-intersecting
polygon
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two toge ...
and the only polygon not to have proper
diagonals
In geometry, a diagonal is a line segment joining two vertices of a polygon or polyhedron, when those vertices are not on the same edge. Informally, any sloping line is called diagonal. The word ''diagonal'' derives from the ancient Greek δ ...
. When doing quick estimates, 3 is a rough approximation of
, 3.1415..., and a very rough approximation of
''e'', 2.71828...
3 is the first
Mersenne prime
In mathematics, a Mersenne prime is a prime number that is one less than a power of two. That is, it is a prime number of the form for some integer . They are named after Marin Mersenne, a French Minim friar, who studied them in the early 17t ...
, as well as the second Mersenne prime exponent and the second
double Mersenne prime exponent, for 7 and
127, respectively. 3 is also the first of five known
Fermat prime
In mathematics, a Fermat number, named after Pierre de Fermat, who first studied them, is a positive integer of the form
:F_ = 2^ + 1,
where ''n'' is a non-negative integer. The first few Fermat numbers are:
: 3, 5, 17, 257, 65537, 4294967 ...
s, which include 5,
17,
257, and
65537
65537 is the integer after 65536 and before 65538.
In mathematics
65537 is the largest known prime number of the form 2^ +1 (n = 4). Therefore, a regular polygon with 65537 sides is constructible with compass and unmarked straightedge. Johann ...
. It is the second
Fibonacci prime
A Fibonacci prime is a Fibonacci number that is prime, a type of integer sequence prime.
The first Fibonacci primes are :
: 2, 3, 5, 13, 89, 233, 1597, 28657, 514229, 433494437, 2971215073, ....
Known Fibonacci primes
It is not known whet ...
(and the second
Lucas prime
The Lucas numbers or Lucas series are an integer sequence named after the mathematician Édouard Lucas, François Édouard Anatole Lucas (1842–1891), who studied both that sequence and the closely related Fibonacci numbers. Lucas numbers a ...
), the second
Sophie Germain prime
In number theory, a prime number ''p'' is a if 2''p'' + 1 is also prime. The number 2''p'' + 1 associated with a Sophie Germain prime is called a . For example, 11 is a Sophie Germain prime and 2 × 11 +  ...
, and the second
factorial prime
A factorial prime is a prime number that is one less or one more than a factorial (all factorials greater than 1 are even).
The first 10 factorial primes (for ''n'' = 1, 2, 3, 4, 6, 7, 11, 12, 14) are :
: 2 (0! +&n ...
, as it is equal to 2! + 1.
3 is the second and only prime
triangular number
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and cube numbers. The th triangular number is the number of dots in ...
, and
Gauss
Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...
proved that every integer is the sum of at most 3
triangular numbers
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and cube numbers. The th triangular number is the number of dots in ...
.
3 is the number of non-collinear points needed to determine a
plane
Plane(s) most often refers to:
* Aero- or airplane, a powered, fixed-wing aircraft
* Plane (geometry), a flat, 2-dimensional surface
Plane or planes may also refer to:
Biology
* Plane (tree) or ''Platanus'', wetland native plant
* ''Planes' ...
and a
circle
A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. Equivalently, it is the curve traced out by a point that moves in a plane so that its distance from a given point is const ...
.
Three is the only prime which is one less than a
perfect square. Any other number which is
− 1 for some integer
is not prime, since it is (
− 1)(
+ 1). This is true for 3 as well (with
= 2), but in this case the smaller factor is 1. If
is greater than 2, both
− 1 and
+ 1 are greater than 1 so their product is not prime.
A
natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...
is
divisible
In mathematics, a divisor of an integer n, also called a factor of n, is an integer m that may be multiplied by some integer to produce n. In this case, one also says that n is a multiple of m. An integer n is divisible or evenly divisible by ...
by three if the
sum of its digits in
base 10
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...
is divisible by 3. For example, the number 21 is divisible by three (3 times 7) and the sum of its digits is 2 + 1 = 3. Because of this, the reverse of any number that is divisible by three (or indeed, any
permutation
In mathematics, a permutation of a set is, loosely speaking, an arrangement of its members into a sequence or linear order, or if the set is already ordered, a rearrangement of its elements. The word "permutation" also refers to the act or proc ...
of its digits) is also divisible by three. For instance, 1368 and its reverse 8631 are both divisible by three (and so are 1386, 3168, 3186, 3618, etc.). See also
Divisibility rule
A divisibility rule is a shorthand and useful way of determining whether a given integer is divisible by a fixed divisor without performing the division, usually by examining its digits. Although there are divisibility tests for numbers in any rad ...
. This works in
base 10
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...
and in any
positional numeral system
Positional notation (or place-value notation, or positional numeral system) usually denotes the extension to any radix, base of the Hindu–Arabic numeral system (or decimal, decimal system). More generally, a positional system is a numeral syste ...
whose
base divided by three leaves a remainder of one (bases 4, 7, 10, etc.).
Three of the five
Platonic solids
In geometry, a Platonic solid is a convex, regular polyhedron in three-dimensional Euclidean space. Being a regular polyhedron means that the faces are congruent (identical in shape and size) regular polygons (all angles congruent and all edges c ...
have triangular faces – the
tetrahedron
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...
, the
octahedron
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...
, and the
icosahedron
In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons".
There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrica ...
. Also, three of the five Platonic solids have
vertices where three faces meet – the
tetrahedron
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...
, the
hexahedron
A hexahedron (plural: hexahedra or hexahedrons) or sexahedron (plural: sexahedra or sexahedrons) is any polyhedron with six faces. A cube, for example, is a regular hexahedron with all its faces square, and three squares around each vertex.
There ...
(
cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. Viewed from a corner it is a hexagon and its net is usually depicted as a cross.
The cube is the only r ...
), and the
dodecahedron
In geometry, a dodecahedron (Greek , from ''dōdeka'' "twelve" + ''hédra'' "base", "seat" or "face") or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagon ...
. Furthermore, only three different types of
polygons
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two toge ...
comprise the faces of the five Platonic solids – the
triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...
, the
square
In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length adj ...
, and the
pentagon
In geometry, a pentagon (from the Greek πέντε ''pente'' meaning ''five'' and γωνία ''gonia'' meaning ''angle'') is any five-sided polygon or 5-gon. The sum of the internal angles in a simple pentagon is 540°.
A pentagon may be simpl ...
.
There are only three distinct 4×4
panmagic square A pandiagonal magic square or panmagic square (also diabolic square, diabolical square or diabolical magic square) is a magic square with the additional property that the broken diagonals, i.e. the diagonals that wrap round at the edges of the squar ...
s.
According to
Pythagoras
Pythagoras of Samos ( grc, Πυθαγόρας ὁ Σάμιος, Pythagóras ho Sámios, Pythagoras the Samos, Samian, or simply ; in Ionian Greek; ) was an ancient Ionians, Ionian Ancient Greek philosophy, Greek philosopher and the eponymou ...
and the
Pythagorean
Pythagorean, meaning of or pertaining to the ancient Ionian mathematician, philosopher, and music theorist Pythagoras, may refer to:
Philosophy
* Pythagoreanism, the esoteric and metaphysical beliefs purported to have been held by Pythagoras
* Ne ...
school, the number 3, which they called ''triad'', is the noblest of all digits, as it is the only number to equal the sum of all the terms below it, and the only number whose sum with those below equals the product of them and itself.
There are three finite convex
uniform polytope groups in three dimensions, aside from the infinite families of
prisms and
antiprisms
In geometry, an antiprism or is a polyhedron composed of two parallel direct copies (not mirror images) of an polygon, connected by an alternating band of triangles. They are represented by the Conway notation .
Antiprisms are a subclass ...
: the
tetrahedral group
150px, A regular tetrahedron, an example of a solid with full tetrahedral symmetry
A regular tetrahedron has 12 rotational (or orientation-preserving) symmetries, and a symmetry order of 24 including transformations that combine a reflection a ...
, the
octahedral group
A regular octahedron has 24 rotational (or orientation-preserving) symmetries, and 48 symmetries altogether. These include transformations that combine a reflection and a rotation. A cube has the same set of symmetries, since it is the polyhedr ...
, and the
icosahedral group
In mathematics, and especially in geometry, an object has icosahedral symmetry if it has the same symmetries as a regular icosahedron. Examples of other polyhedra with icosahedral symmetry include the regular dodecahedron (the dual of the ...
. In dimensions
⩾ 5, there are only three regular polytopes: the
-
simplex
In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions. The simplex is so-named because it represents the simplest possible polytope in any given dimension. ...
es,
-
cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. Viewed from a corner it is a hexagon and its net is usually depicted as a cross.
The cube is the only r ...
s, and
-
orthoplex
In geometry, a cross-polytope, hyperoctahedron, orthoplex, or cocube is a regular, convex polytope that exists in ''n''- dimensional Euclidean space. A 2-dimensional cross-polytope is a square, a 3-dimensional cross-polytope is a regular octahed ...
es. In dimensions
⩾
9, the only three uniform polytope families, aside from the numerous infinite
proprism
In geometry of 4 dimensions or higher, a proprism is a polytope resulting from the Cartesian product of two or more polytopes, each of two dimensions or higher. The term was coined by John Horton Conway for ''product prism''. The dimension of the s ...
atic families, are the
simplex,
cubic, and
demihypercubic families. For
paracompact hyperbolic honeycombs, there are three groups in
dimension
In physics and mathematics, the dimension of a Space (mathematics), mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any Point (geometry), point within it. Thus, a Line (geometry), lin ...
s
6 and
9, or equivalently of ranks 7 and 10, with no other forms in higher dimensions. Of the final three groups, the largest and most important is
, that is associated with an important
Kac–Moody Lie algebra
In mathematics, a Lie algebra (pronounced ) is a vector space \mathfrak g together with an Binary operation, operation called the Lie bracket, an Alternating multilinear map, alternating bilinear map \mathfrak g \times \mathfrak g \rightarrow ...
.
The
trisection of the angle
Angle trisection is a classical problem of straightedge and compass construction of ancient Greek mathematics. It concerns construction of an angle equal to one third of a given arbitrary angle, using only two tools: an unmarked straightedge an ...
was one of the three famous problems of antiquity.
Numeral systems
There is some evidence to suggest that early man may have used counting systems which consisted of "One, Two, Three" and thereafter "Many" to describe counting limits. Early peoples had a word to describe the quantities of one, two, and three but any quantity beyond was simply denoted as "Many". This is most likely based on the prevalence of this phenomenon among people in such disparate regions as the deep Amazon and Borneo jungles, where western civilization's explorers have historical records of their first encounters with these indigenous people.
List of basic calculations
Science
*The Roman numeral III stands for
giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moo ...
in the
Yerkes spectral classification scheme
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...
.
*Three is the
atomic number
The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...
of
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
.
*Three is the
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
code of "
End of Text
The End-of-Text character (ETX) is a control character used to inform the receiving computer that the end of a record has been reached. This may or may not be an indication that all of the data in a record have been received. In ASCII and in EBCD ...
".
*Three is the number of
dimensions
In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordina ...
that humans can perceive. Humans perceive the
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...
to have
three spatial dimensions, but some theories, such as
string theory
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interac ...
, suggest there are more.
*Three is the number of elementary fermion
generations
A generation is "all of the people born and living at about the same time, regarded collectively."
Generation or generations may also refer to:
Science and technology
* Generation (particle physics), a division of the elementary particles
* Gen ...
according to the
Standard Model
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying a ...
of particle physics.
*The
triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...
, a
polygon
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two toge ...
with three
edges and three
vertices, is the most stable physical shape. For this reason it is widely utilized in construction, engineering and design.
*The ability of the
human eye
The human eye is a sensory organ, part of the sensory nervous system, that reacts to visible light and allows humans to use visual information for various purposes including seeing things, keeping balance, and maintaining circadian rhythm.
...
to distinguish
color
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...
s is based upon the varying sensitivity of different cells in the
retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
to light of different
wavelengths
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...
. Humans being
trichromatic
Trichromacy or trichromatism is the possessing of three independent channels for conveying color information, derived from the three different types of cone cells in the eye. Organisms with trichromacy are called trichromats.
The normal expl ...
, the retina contains three types of color receptor cells, or
cones
A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex.
A cone is formed by a set of line segments, half-lines, or lines conn ...
.
*There are three
primary color
A set (mathematics), set of primary colors or primary colours (see American and British English spelling differences#-our, -or, spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamu ...
s in the
additive
Additive may refer to:
Mathematics
* Additive function, a function in number theory
* Additive map, a function that preserves the addition operation
* Additive set-functionn see Sigma additivity
* Additive category, a preadditive category with f ...
and
subtractive models.
Protoscience
*In European
alchemy
Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...
, the three primes ( la, tria prima) were
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
(
![Salt symbol (alchemical)](https://upload.wikimedia.org/wikipedia/commons/0/06/Salt_symbol_%28alchemical%29.svg)
),
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
() and
mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
().
[Eric John Holmyard. ''Alchemy.'' 1995. p.153]
*The three
doshas
''Dosha'' ( sa, दोषः, IAST: ''doṣa'') is a central term in Ayurveda originating from Sanskrit, which can be translated as "that which can cause problems" (literally meaning "fault" or "defect"), and which refers to three categories o ...
(weaknesses) and their
antidote
An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are s ...
s are the basis of
Ayurvedic medicine
Ayurveda () is an alternative medicine system with historical roots in the Indian subcontinent. The theory and practice of Ayurveda is pseudoscientific. Ayurveda is heavily practiced in India and Nepal, where around 80% of the population rep ...
in India.
Pseudoscience
*Three is the symbolic representation for
Mu,
Augustus Le Plongeon
Augustus Henry Julian Le Plongeon (4 May 1825 – 13 December 1908) was a British-American archeologist and photographer who studied the pre-Columbian ruins of America, particularly those of the Maya civilization on the northern Yucatán Penins ...
's and
James Churchward
James Churchward (27 February 1851 – 4 January 1936) was a British occult writer, inventor, engineer, and fisherman.
Churchward is most notable for proposing the existence of a lost continent, called " Mu," in the Pacific Ocean. His writings o ...
's lost continent.
*In Pythagorean
numerology
Numerology (also known as arithmancy) is the belief in an occult, divine or mystical relationship between a number and one or more coinciding events. It is also the study of the numerical value, via an alphanumeric system, of the letters in ...
the number 3 is the digit that represents the communication. It encourages the expansion of creativity, sociability between people and movement. For Pythagoras, the number 3 was a perfect number, representing harmony, perfection, and divine proportion.
Philosophy
*Philosophers such as
Aquinas
Thomas Aquinas, OP (; it, Tommaso d'Aquino, lit=Thomas of Aquino; 1225 – 7 March 1274) was an Italian Dominican friar and priest who was an influential philosopher, theologian and jurist in the tradition of scholasticism; he is known wit ...
,
Kant
Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German Philosophy, philosopher and one of the central Age of Enlightenment, Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemolo ...
,
Hegel
Georg Wilhelm Friedrich Hegel (; ; 27 August 1770 – 14 November 1831) was a German philosopher. He is one of the most important figures in German idealism and one of the founding figures of modern Western philosophy. His influence extends a ...
,
C. S. Peirce, and
Karl Popper
Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British philosopher, academic and social commentator. One of the 20th century's most influential philosophers of science, Popper is known for his rejection of the cl ...
have made threefold divisions, or ''
trichotomies'', which have been important in their work.
*
Hegel
Georg Wilhelm Friedrich Hegel (; ; 27 August 1770 – 14 November 1831) was a German philosopher. He is one of the most important figures in German idealism and one of the founding figures of modern Western philosophy. His influence extends a ...
's
dialectic
Dialectic ( grc-gre, διαλεκτική, ''dialektikḗ''; related to dialogue; german: Dialektik), also known as the dialectical method, is a discourse between two or more people holding different points of view about a subject but wishing ...
of
Thesis + Antithesis = Synthesis creates three-ness from two-ness.
Religion
![Triple-Goddess-Waxing-Full-Waning-Symbol](https://upload.wikimedia.org/wikipedia/commons/c/cb/Triple-Goddess-Waxing-Full-Waning-Symbol.svg)
Many world religions contain triple deities or concepts of trinity, including:
*The
Hindu
Hindus (; ) are people who religiously adhere to Hinduism.Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for ...
Trimurti
The Trimūrti (; Sanskrit: त्रिमूर्ति ', "three forms" or "trinity") are the trinity of supreme divinity in Hinduism, in which the cosmic functions of creation, maintenance, and destruction are personified as a triad of de ...
*The Hindu
Tridevi
The Tridevi () are a trinity of supreme divinity in Hinduism, joining a triad of eminent goddesses either as a feminine version of the Trimurti, or as consorts of a masculine Trimurti, depending on the denomination. This triad is typically p ...
*The
Three Jewels
In Buddhism, refuge or taking refuge refers to a religious practice, which often includes a prayer or recitation performed at the beginning of the day or of a practice session. Since the period of Early Buddhism until present time, all Theravada ...
of
Buddhism
Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the Buddha. It originated in northern India as a -movement in the 5th century BCE, and gra ...
*The
Three Pure Ones
The Three Pure Ones (), also translated as the Three Pure Pellucid Ones, the Three Pristine Ones, the Three Divine Teachers, the Three Clarities, or the Three Purities, are the three highest gods in the Taoist pantheon. They are regarded as pure ...
of
Taoism
Taoism (, ) or Daoism () refers to either a school of Philosophy, philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of China, Chinese origin and emphasize living in harmo ...
*The
Christian
Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χρι ...
Holy Trinity
The Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God the F ...
*The
Triple Goddess of
Wicca
Wicca () is a modern Pagan religion. Scholars of religion categorise it as both a new religious movement and as part of the occultist stream of Western esotericism. It was developed in England during the first half of the 20th century and was ...
Christianity
*The
threefold office
The threefold office ( la, munus triplex) of Jesus Christ is a Christian doctrine based upon the teachings of the Old Testament of which Christians hold different views. It was described by Eusebius and more fully developed by John Calvin.
The ...
of
Christ
Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label=Hebrew/Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (among other Names and titles of Jesus in the New Testament, names and titles), was ...
is a Christian doctrine which states that Christ performs the functions of
prophet
In religion, a prophet or prophetess is an individual who is regarded as being in contact with a divine being and is said to speak on behalf of that being, serving as an intermediary with humanity by delivering messages or teachings from the s ...
,
priest
A priest is a religious leader authorized to perform the sacred rituals of a religion, especially as a mediatory agent between humans and one or more deities. They also have the authority or power to administer religious rites; in particu ...
, and
king
King is the title given to a male monarch in a variety of contexts. The female equivalent is queen, which title is also given to the consort of a king.
*In the context of prehistory, antiquity and contemporary indigenous peoples, the tit ...
.
*The
ministry of Jesus
The ministry of Jesus, in the canonical gospels, begins with his baptism in the countryside of Roman Judea and Transjordan, near the River Jordan by John the Baptist, and ends in Jerusalem, following the Last Supper with his disciples.''Chri ...
lasted approximately three years.
*During the
Agony in the Garden
The Agony in the Garden of Gethsemane is an episode in the life of Jesus. After the Last Supper, Jesus enters a garden where he experiences great anguish and prays to be delivered from his impending death on the cross ("Take this cup from me") ...
, Christ asked three times for the cup to be taken from him.
*Jesus
rose from the dead on the third day after his death.
*The
devil tempted Jesus three times.
*
Saint Peter
Saint Peter; he, שמעון בר יונה, Šimʿōn bar Yōnāh; ar, سِمعَان بُطرُس, translit=Simʿa̅n Buṭrus; grc-gre, Πέτρος, Petros; cop, Ⲡⲉⲧⲣⲟⲥ, Petros; lat, Petrus; ar, شمعون الصفـا, Sham'un ...
thrice denied Jesus and
thrice affirmed his faith in Jesus.
*The
Magi
Magi (; singular magus ; from Latin ''magus'', cf. fa, مغ ) were priests in Zoroastrianism and the earlier religions of the western Iranians. The earliest known use of the word ''magi'' is in the trilingual inscription written by Darius th ...
– wise men who were astronomers/astrologers from Persia – gave Jesus three gifts.
*There are three
Synoptic Gospels
The gospels of Gospel of Matthew, Matthew, Gospel of Mark, Mark, and Gospel of Luke, Luke are referred to as the synoptic Gospels because they include many of the same stories, often in a similar sequence and in similar or sometimes identical ...
and three
epistles of John
The Johannine epistles, the Epistles of John, or the Letters of John are three of the catholic epistles of the New Testament, thought to have been written between 85 and 100 AD. Most scholars agree that all three letters are written by the same a ...
.
*
Paul the Apostle
Paul; grc, Παῦλος, translit=Paulos; cop, ⲡⲁⲩⲗⲟⲥ; hbo, פאולוס השליח (previously called Saul of Tarsus;; ar, بولس الطرسوسي; grc, Σαῦλος Ταρσεύς, Saũlos Tarseús; tr, Tarsuslu Pavlus; ...
went blind for three days after his
conversion to Christianity
Conversion to Christianity is the religious conversion of a previously non-Christian person to Christianity. Different Christian denominations may perform various different kinds of rituals or ceremonies initiation into their community of believ ...
.
Judaism
*
Noah
Noah ''Nukh''; am, ኖህ, ''Noḥ''; ar, نُوح '; grc, Νῶε ''Nôe'' () is the tenth and last of the pre-Flood patriarchs in the traditions of Abrahamic religions. His story appears in the Hebrew Bible (Book of Genesis, chapters 5– ...
had three sons:
Ham
Ham is pork from a leg cut of pork, cut that has been food preservation, preserved by wet or dry Curing (food preservation), curing, with or without smoking (cooking), smoking."Bacon: Bacon and Ham Curing" in ''Chambers's Encyclopædia''. Lo ...
,
Shem
Shem (; he, שֵׁם ''Šēm''; ar, سَام, Sām) ''Sḗm''; Ge'ez: ሴም, ''Sēm'' was one of the sons of Noah in the book of Genesis and in the book of Chronicles, and the Quran.
The children of Shem were Elam, Ashur, Arphaxad, L ...
and
Japheth
Japheth ( he, יֶפֶת ''Yép̄eṯ'', in pausa ''Yā́p̄eṯ''; el, Ἰάφεθ '; la, Iafeth, Iapheth, Iaphethus, Iapetus) is one of the three sons of Noah in the Book of Genesis, in which he plays a role in the story of Noah's drunk ...
*The Three
Patriarchs
The highest-ranking bishops in Eastern Orthodoxy, Oriental Orthodoxy, the Catholic Church (above major archbishop and primate (bishop), primate), the Hussite Church, Church of the East, and some Independent Catholicism, Independent Catholic Chur ...
:
Abraham
Abraham, ; ar, , , name=, group= (originally Abram) is the common Hebrew patriarch of the Abrahamic religions, including Judaism, Christianity, and Islam. In Judaism, he is the founding father of the special relationship between the Jew ...
,
Isaac
Isaac; grc, Ἰσαάκ, Isaák; ar, إسحٰق/إسحاق, Isḥāq; am, ይስሐቅ is one of the three patriarchs of the Israelites and an important figure in the Abrahamic religions, including Judaism, Christianity, and Islam. He was the ...
and
Jacob
Jacob (; ; ar, يَعْقُوب, Yaʿqūb; gr, Ἰακώβ, Iakṓb), later given the name Israel, is regarded as a patriarch of the Israelites and is an important figure in Abrahamic religions, such as Judaism, Christianity, and Islam. J ...
*The prophet
Balaam
Balaam (; , Standard ''Bīlʿam'' Tiberian ''Bīlʿām'') is a diviner in the Torah (Pentateuch) whose story begins in Chapter 22 of the Book of Numbers (). Ancient references to Balaam consider him a non-Israelite, a prophet, and the son of Beo ...
beat his donkey three times.
*The prophet Jonah spent three days and nights in the belly of a large fish
*Three divisions of the Written Torah: Torah (Five Books of Moses), Nevi'im (Prophets), Ketuvim (Writings)
*Three divisions of the Jewish people: Kohen, Levite, Yisrael
*Three daily Jewish prayer, prayers: ''Shacharit'', ''Mincha'', ''Maariv''
*Three Shabbat meals
*Shabbat ends when three stars are visible in the night sky
*Three Pilgrimage Festivals: Passover, Shavuot, Sukkot
*Three matzos on the Passover Seder table
*The Three Weeks, a period of mourning bridging the fast days of Seventeenth of Tammuz and Tisha B'Av
*Three cardinal sins for which a Jew must die rather than transgress: Idolatry#Judaism, idolatry, murder, Immorality#Sexual immorality, sexual immorality
*Upsherin, a Jewish boy's first haircut at age 3
*A Beth din is composed of three members
*Potential Conversion to Judaism, converts are traditionally turned away three times to test their sincerity
*In the Jewish mysticism, Jewish mystical tradition of the Kabbalah, it is believed that the soul consists of three parts, with the highest being ''Soul#Judaism, neshamah'' ("breath"), the middle being ''ruach'' ("wind" or "spirit") and the lowest being ''Nephesh, nefesh'' ("repose"). Sometimes the two elements of ''Chayah'' ("life" or "animal") and ''Yechidah'' ("unit") are additionally mentioned.
*In the Kabbalah, the Tree of life (Kabbalah), Tree of Life (Hebrew: ''Etz ha-Chayim'', עץ החיים) refers to a latter 3-pillar diagrammatic representation of its central mystical symbol, known as the ''Sephirot, 10 Sephirot''.
Islam
*The three core principles in Shia tradition: Tawhid (Oneness of God), Nabuwwa (Concept of Prophethood), Imama (Concept of Imam)
Buddhism
*The Triple Bodhi (ways to understand the end of birth) are Budhu, Pasebudhu, and Mahaarahath.
*The
Three Jewels
In Buddhism, refuge or taking refuge refers to a religious practice, which often includes a prayer or recitation performed at the beginning of the day or of a practice session. Since the period of Early Buddhism until present time, all Theravada ...
, the three things that Buddhists take Refuge (Buddhism), refuge in.
Shinto
*The Imperial Regalia of Japan of the sword, mirror, and jewel.
Daoism
*The Three Treasures (Taoism), Three Treasures (), the basic virtues in
Taoism
Taoism (, ) or Daoism () refers to either a school of Philosophy, philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of China, Chinese origin and emphasize living in harmo ...
.
*The Three Dantians
*Three Lines of a Ba Gua, Trigram
*Three Sovereigns: Heaven Fu Xi (Hand – Head – 3º Eye), Humanity Shen Nong (Liang Yi, Unit 69), Hell Nüwa (Foot – Abdomen – Umbiculus).
Hinduism
*The
Trimurti
The Trimūrti (; Sanskrit: त्रिमूर्ति ', "three forms" or "trinity") are the trinity of supreme divinity in Hinduism, in which the cosmic functions of creation, maintenance, and destruction are personified as a triad of de ...
: Brahma the Creator, Vishnu the Preserver, and Shiva the Destroyer.
*The three Gunas found in Samkhya school of Hindu philosophy.
*The three paths to salvation in the ''Bhagavad Gita'' named Karma Yoga, Bhakti Yoga and Jnana Yoga.
Zoroastrianism
*The three virtues of ''Humata'', ''Hukhta'' and ''Huvarshta'' (Good Thoughts, Good Words and Good Deeds) are a basic tenet in Zoroastrianism.
Norse mythology
Three is a very significant number in Norse mythology, along with its powers 9 and 27.
*Prior to Ragnarök, there will be three hard winters without an intervening summer, the Fimbulwinter.
*Odin endured three hardships upon the World Tree in his quest for the runic alphabet, runes: he hanged himself, wounded himself with a spear, and suffered from hunger and thirst.
*Borr, Bor had three sons, Odin, Vili, and Vé.
Other religions
*The
Wicca
Wicca () is a modern Pagan religion. Scholars of religion categorise it as both a new religious movement and as part of the occultist stream of Western esotericism. It was developed in England during the first half of the 20th century and was ...
n Rule of Three (Wiccan), Rule of Three.
*The
Triple Goddess: Maiden, Mother, Crone; the three fates.
*The sons of Cronus: Zeus, Poseidon, and Hades.
*The Slavic god Triglav (mythology), Triglav has three heads.
Esoteric tradition
*The Theosophical Society has Theosophy (Blavatskian), three conditions of membership.
*Gurdjieff's Three Centres, Three Centers and the Fourth Way, Law of Three.
*''Liber AL vel Legis'', the central scripture of the religion of Thelema, consists of three chapters, corresponding to three divine narrators respectively: Nuit, Hadit and Ra-Hoor-Khuit.
*The Triple Greatness of Hermes Trismegistus is an important theme in Hermeticism.
As a lucky or unlucky number
Three (, formal writing: , pinyin ''sān'', Cantonese: ''saam''
1) is considered a numerology, good number in Chinese culture because it sounds like the word "alive" ( pinyin ''shēng'', Cantonese: ''saang''
1), compared to 4 (number), four (, pinyin: ''sì'', Cantonese: ''sei''
1), which sounds like the word "death" ( pinyin ''sǐ'', Cantonese: ''sei''
2).
Counting to three is common in situations where a group of people wish to perform an action in Synchronization, synchrony: ''Now, on the count of three, everybody pull!'' Assuming the counter is proceeding at a uniform rate, the first two counts are necessary to establish the rate, and the count of "three" is predicted based on the timing of the "one" and "two" before it. Three is likely used instead of some other number because it requires the minimal amount counts while setting a rate.
There is another superstition that it is unlucky to take a Three on a match (superstition), third light, that is, to be the third person to light a cigarette from the same match or lighter. This superstition is sometimes asserted to have originated among soldiers in the trenches of the First World War when a sniper might see the first light, take aim on the second and fire on the third.
The phrase ":wikt:Third time's the charm, Third time's the charm" refers to the superstition that after two failures in any endeavor, a third attempt is more likely to succeed. This is also sometimes seen in reverse, as in "third man [to do something, presumably forbidden] gets caught".
Luck, especially bad luck, is often said to "come in threes".
[See]
bad
in the ''Oxford Dictionary of Phrase and Fable'', 2006, via Encyclopedia.com.
Sports
* In American football, American and Canadian football, a field goal is worth three points.
*In association football:
** For purposes of league standings, since the mid-1990s almost all leagues have awarded three points for a win.
** A team that wins three trophies in a season is said to have won a Treble (association football), treble.
** A player who scores three goals in a match is said to have scored a hat-trick.
* In baseball:
** A batter Strikeout, strikes out upon the third Strike zone, strike in any single batting appearance.
** Each team's half of an inning ends once the defense has recorded three outs (unless the home team has a Walk-off home run, walk-off hit in the ninth inning or any extra inning).
** In scorekeeping, "3" denotes the first baseman.
*In basketball:
** Three-point field goal, Three points are awarded for a basket made from behind a designated arc on the floor.
** The "3 position" is the small forward.
*In bowling, three strike (bowling), strikes bowled consecutively is known as a "turkey".
* In cricket, a bowler who is credited with dismissals of batsmen on three consecutive deliveries has achieved a "hat-trick".
*In Gaelic games (Gaelic football for Gaelic football, men and Ladies' Gaelic football, women, hurling, and camogie), three points are awarded for a goal, scored when the ball passes underneath the crossbar and between the goal posts.
*In ice hockey:
** Scoring three goals is called a "hat trick" (usually not hyphenated in North America).
** A team will typically have three Forward (ice hockey), forwards on the ice at any given time.
* In professional wrestling, a pin (professional wrestling), pin is when one holds the opponent's shoulders against the mat for a count of three.
* In rugby union:
** A successful Penalty (rugby union), penalty kick for goal or drop goal is worth three points.
** In the National Rugby League (France), French variation of the Rugby union bonus points system, bonus points system, a team receives a bonus point in the league standings if it wins a match while scoring at least three more tries than its opponent.
** The starting Rugby union positions, tighthead prop wears the jersey number 3.
* In rugby league:
** One of the two starting centres wears the jersey number 3. (An exception to this rule is the Super League, which uses static squad numbering.)
*A "threepeat" is a term for winning three consecutive championships.
*A triathlon consists of three events: swimming, bicycling, and running.
*In many sports a competitor or team is said to win a Triple Crown (disambiguation), Triple Crown if they win three particularly prestigious competitions.
* In volleyball, once the ball is served, teams are allowed to touch the ball three times before being required to return the ball to the other side of the court, with the definition of "touch" being slightly different between indoor and beach volleyball.
Film
*A number of film versions of the novel ''The Three Musketeers'' by Alexandre Dumas: (The Three Musketeers (1921 film), 1921, The Three Musketeers (1933 serial), 1933, The Three Musketeers (1948 film), 1948, The Three Musketeers (1973 live-action film), 1973, 1992, The Three Musketeers (1993 film), 1993 and The Three Musketeers (2011 film), 2011).
*''3 Days of the Condor'' (1975), starring Robert Redford, Faye Dunaway, Cliff Robertson, and Max von Sydow.
*''Three Amigos'' (1986), comedy film starring Steve Martin, Chevy Chase, and Martin Short.
*''Three Kings (1999 film), Three Kings'' (1999), starring George Clooney, Mark Wahlberg, Ice Cube, and Spike Jonze.
*''3 Days to Kill'' (2014), starring Kevin Costner.
*''Three Billboards Outside Ebbing, Missouri'' (2017), starring Frances McDormand, Woody Harrelson, Sam Rockwell.
See also
*Cube (algebra) – (3 superscript)
*Third (disambiguation), Third
*Triad (disambiguation), Triad
*Rule of three (disambiguation), Rule of three
*List of highways numbered 3
References
*Wells, D. ''The Penguin Dictionary of Curious and Interesting Numbers'' London: Penguin Group. (1987): 46–48
External links
Tricyclopedic Book of Threesby Michael Eck
by Dr. John A. McNulty
*
The Number 3The Positive Integer 3
{{DEFAULTSORT:3 (Number)
Integers
3 (number),